A comparison of the mechanisms controlling the hatching time and synchrony of the desert locust Schistocerca gregaria an
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ORIGINAL RESEARCH PAPER
A comparison of the mechanisms controlling the hatching time and synchrony of the desert locust Schistocerca gregaria and the Bombay locust Nomadacris succincta (Orthoptera: Acrididae) Seiji Tanaka1,2 Received: 3 August 2020 / Accepted: 23 September 2020 © The Japanese Society of Applied Entomology and Zoology 2020
Abstract Hatching behaviors of the desert locust Schistocerca gregaria (Forskål) (Orthoptera: Acrididae) and the Bombay locust Nomadacris succincta (Johannson 1763) (Orthoptera: Acrididae) were observed to analyze the mechanisms controlling the hatching time and synchrony. At a 12-h thermoperiod of 25 °C and 30 °C under continuous illumination, most eggs hatched during the low temperature period in the desert locust, and the proportion of such individuals was lower in eggs kept in a mass than in those kept singly. In the Bombay locust, most eggs hatched during the high temperature period; however, the inter-pod variation was large. Both locusts hatched earlier with increasing the egg mass size in a range from 2 to 10 or 20 with similar hatching intervals. Desert locust eggs from different pods advanced the hatching but did not delay it to synchronize the hatching. In contrast, Bombay locust eggs advanced or delayed hatching depending on the age of the paired egg. The results suggested the presence of embryo–embryo interactions. In both locusts, a vibrational stimulus that was emitted by the embryo and transmitted via a piece of wire was likely to be responsible for synchronized hatching. The hatching patters of these species were compared with those reported previously for other taxa. Keywords Hatching · Nomadacris succincta · Schistocerca gregaria · Thermoperiod · Vibration
Introduction Hatching is one of the most vulnerable moments in insect life. Newly hatched nymphs or larvae may be susceptible to environmental extremes and may not be able to move quickly upon an attack by a predator until their body becomes hardened. These problems might partly explain why insect eggs in general hatch at a particular time of the day, although the hatching time may depend on the species. Many species use environmental cues such as photoperiod, temperature and moisture to control the hatching timing (Danks 1987; Saunders 2002; Tauber et al. 1986). In the migratory locust, Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13355-020-00702-w) contains supplementary material, which is available to authorized users. * Seiji Tanaka [email protected] 1
Former National Institute of Agro-biological Sciences at Ohwashi (NIASO), Tsukuba, Ibaraki 305‑8634, Japan
Matsushiro 1‑20‑19, Tsukuba, Ibaraki 305‑0035, Japan
2
Locusta migratoria L. (Orthoptera: Acrididae), eggs hatch during the light period in a 12-h photoperiod at a constant temperature, whereas they hatch during the high-temperature period in a 12-h thermoperiod under continuous illumination (Nishide et al. 2015a). These observations are consistent with field observations that egg h
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